Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
Whelp, had a bit of a test night and found a few things are yay and a few are nay.
- seatbelt tether + wheely bar. Ended up being ripped out where it bolts on, Was only two m5s so i'll need to upgrade it to x4 and hopefully that'll contain the seat belt too, otherwise i might need to look into looping it over something then sewing it.
- ram seems fixed. Didn't get jammed all night, sweet.
- bungee works, arm came back each time and didn't snap even after the seat belt broke.
- drives - to their credit they worked fine the whole night, one is still grindy though so i'll try rectify it before the nats. I also need to give it more ground clearance as that's an issue.
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
Yeah it does the job, saws go through it quick but the stuff is very cheap and easy to cut so i just replace it all regularly _________________ www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz
Wed Sep 16, 2015 2:53 pm
haz
Joined: 15 Aug 2011
Posts: 169
I like the new look on flips man, awesome.
also you might like this. Girl I work with's brother works for Barr... I mention that I like Iron Bru. Came in to this today lol
Joined: 15 Nov 2013
Posts: 111
Location: Ripon, United Kingdom
If you need any info or help with the seat belts Glen, I may be able to offer some advice. My final year university project was based around seat belts and safety systems.
What you just sad is probably the easiest option, stick it back on itself and run a bar through it that slots into the bulk heads. Or you can clamp it between a pair of zig-zaging Alu plates to make sure you get a really good grip on it, then bolt that to the base plate. You just need to spread the load far enough.
Thu Sep 17, 2015 11:02 pm
Knightrous Site Admin
Joined: 15 Jun 2004
Posts: 8511
Location: NSW
Or go to pick n pay less and get a center rear seat belt and use the pre made clamps and tabs from the car. _________________ https://www.halfdonethings.com/
Fri Sep 18, 2015 8:41 am
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
Small update
So at the vivid event flips was having problems closing, some mystery crud was getting into the vent hole. Resulting in the loss to an 8 year old, clearly unacceptable.
The application of said epoxy may be described as liberal perhaps?
Unfortunately there's not really a better way of doing the plumbing than epoxy, because of all the fixed angle relationships, you can't do about 3 of the fittings up tight.
So we are going to re-do the plumbing with thicker epoxy and keep it to the back half of the fittings.
Also changed the vent port to this.
http://i.imgur.com/jGlY8Zi.jpg
Basically got the bolt head over a milled out bit so that a single piece of crud can't block the hole.It's like a filter.
In terms of making things better the ram has been "ported" to let it come down faster.
http://i.imgur.com/jP0pNha.jpg
Hard to see here but there are now 6x 2mm holes in the side of the ram that should vent it when it reaches the end of the stroke. The leadin was cut with the dremel and crossed fingers then polished with 400 grit. Hopefully it won't wind up cutting up the O Ring as it goes past the ports. _________________ Mechanical engineers build weapons, civil engineers build targets
Fri Aug 05, 2016 12:31 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Are the vents in the side like the ones I proposed for my ram? I think they will be a huge help in retracting the ram but others suggested that the pressure on the up stroke will extrude the O-ring into the holes and then snip a section out of it as it moves past the holes. I will be keen to see how the mods work out. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Fri Aug 05, 2016 1:21 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
yeah side ports, The vent holes are fairly small and there is a soft lead in and out so fingers crossed.The o-ring isn't heavily loaded either which should help.
So today was re-assembly day
step 1 through 12 clean everything
scrape all the old epoxy out then acetone wash and wipe every piece. Then dry assemble it and measure the critical dimensions.
Then pack the threads with 1Hr cure epoxy, leaving the first few turns free of goo (hopefully) to minimise the amount that could get into the system.
Then assemble it all 3 times because you did stupid crap like put the valve in backwards, or forgot to thread the whole thing through the mount first.
Still came out nice though, decent bead on the end of all the threads, I'll leak test it on Tuesday see how it goes. _________________ Mechanical engineers build weapons, civil engineers build targets
Fri Aug 05, 2016 5:39 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
Looking good - maybe Steve should just post you the trophy in advance! _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Fri Aug 05, 2016 6:39 pm
Glen Experienced Roboteer
Joined: 16 Jun 2004
Posts: 9481
Location: Where you least expect
Looking good I think the o ring will be fine but you could also try get your hands on a proper pneumatic piston seal which would be much more durable. Probably run more freely in the cylinder too. _________________ www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz
Fri Aug 05, 2016 8:56 pm
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
That compressor oil is the stuff!
hydraulic oil and some dry lube stuff had heaps of stick/slip going on, the compressor oil is super slippery and one presumes ok with O rings lol.
I have a few spare O rings as well, its not the end of the world to replace the O ring at the event, I cut the plug off the right side of the cylinder so it all just drops in and out fairly easily now. _________________ Mechanical engineers build weapons, civil engineers build targets
Sat Aug 06, 2016 1:10 am
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
I had a look at piston seals, and while they probably have lower friction, they don't look like they will work with the fast exhaust holes in the side of the cylinder. Here is a page with good example pictures:
http://tinyurl.com/z6fykk3
.
The thin lips on most of those seals are more likely to get damaged by the vent holes than an O ring IMHO. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum